Nm In Experiments Research Articles

Li2NaB3S2O12: A Deep-UV Transparent Borosulfate with Moderate Birefringence Derived from the [B3S2O12]∞ Infinite Chain Designed by the High Boron-to-Sulfur Ratio Strategy.

The first mixed alkali metal borosulfate compound, Li2NaB3S2O12 (LNBSO), which contains [BO3] groups, was designed and synthesized by using a high boron-to-sulfur ratio strategy through the high temperature solution method. LNBSO exhibits a birefringence of 0.057@546.1 nm in experiments, which was mainly contributed by the [BO3] groups, and possesses a short absorption edge at 184 nm, and the space group of LNBSO is P21/c. This newly synthesized borosulfate compound holds potential as a promising birefringent material within the deep-ultraviolet wavelength range. Moreover, the investigation on the relationship among the ratio of boron to sulfur, the dimensionality of the anionic framework, and the formation of [BO3] groups has been conducted on available borosulfate, providing insights for the synthesis of borosulfate with desirable performances.

Size tuning of Pt nanoparticles on ZrO2: Optimizing catalytic performance for hydrogen evolution and water-splitting reactions - A DFT study

In heterogeneous catalysis, determining the optimal metal particle size is challenging due to the intricate relationship between particle size, electronic structure, and activity. Here, we investigate the size-dependent activity of Pt nanoparticle (PtNP)-based ZrO2 catalyst for hydrogen evolution reaction (HER) and water-splitting reaction (WSR) using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. By analyzing different Pt nanoparticle sizes (Pt4, Pt7, Pt11, P15, Pt19, and Pt25) supported on ZrO2, we determined their optimized geometries, and electronic structures, and calculated the hydrogen adsorption energies (ΔGH) for HER and activation energies barrier (Δ‡G) for WSR. The calculated results demonstrate that Pt11 is the optimal size for HER, exhibiting the lowest ΔGH (−0.066 eV), while Pt15 shows the lowest Δ‡G (0.24 eV) for WSR. The density of states (DOS) shows that the occupied Pt states fill the gap of ZrO2 (3.72 eV), significantly reducing the band gap (Eg) of the PtNP/ZrO2 composites. The most favorable configuration of the PtNP on ZrO2 for HER and WSR is determined to be a three-Pt-layer structure with rooflike edges which corresponds to a nanoparticle size of ∼0.70–1.55 nm for experiments. These findings can be regarded as an effort toward the design and optimization of metal-based oxide catalysts for renewable energy applications.

Parabolic MMI Coupler for 2 × 2 Silicon Optical Switch With Robustly High Extinction Ratio for Four Paths

We propose and experimentally demonstrate a Mach-Zehnder silicon thermo-optic switch based on a parabolic multi-mode interference coupler. By judiciously designing the parabolic structure, the 2×2 MMI can exhibit extremely small imbalance of output power around 0.1 dB over the C band with good fabrication tolerance according to simulation. As such, for all four possible switching paths, high average extinction ratios over 35 dB can be achieved from 1520 nm to 1580 nm in experiment, with maximum values concurrently over 40 dB. The proposed parabolic MMI occupies a small area of merely 2.4 μm × 9.5 μm.

Efficient Fiber‐to‐Chip Interface via an Intermediated CdS Nanowire

AbstractAn efficient fiber‐to‐chip interface via an intermediated CdS nanowire is demonstrated. The fiber mode is firstly squeezed through a fiber taper drawn at the end of a single‐mode fiber, then evanescently coupled into an intermediated CdS nanowire with a longitudinally tapering profile, and finally coupled into an on‐chip silicon waveguide (SiW) via a waveguide taper fabricated on it. Since the fiber‐nanowire‐SiW cascade structure is designed to match effective indices in each coupling area, such a fiber‐to‐chip interface ensures a bidirectional coupling efficiency up to 90% and a 3‐dB bandwidth over 100 nm in experiments. The difference of coupling efficiencies between the TM or TE modes is less than 0.5 dB in the spectral range of 1545–1635 nm. The footprint of the on‐chip coupling structure is about 10 µm in size. The results may provide a compact, efficient, and versatile fiber‐to‐chip interface in applications including optical interconnects, coherent communication, and quantum optical circuitry.

Design and disturbance rejection control of a piezoelectric nanopositioning stage

The article covers structural design and disturbance rejection control of a flexure-based compliant piezoelectric nanopositioning stage. The stage is devised using four-bar amplification mechanisms, auxiliary guiding mechanisms, and a compound parallelogram mechanism. Static and dynamic models of compliant mechanisms are analyzed based on a compliance matrix method. A modified Prandtl-Ishlinskii (PI) model with dead zone operators is used to describe the asymmetric hysteresis. Then, a global electromechanical dynamic model is built and identified. A comprehensive disturbance rejection controller (CDRC) combining a robust H∞ control and a disturbance observer-based (DOB) control is proposed for high trajectory tracking accuracy and anti-disturbance performance. The trajectory tracking accuracy of the stage can be up to 3 nm in experiments. As amplitudes of reference signals increases, relative tracking errors gradually decrease. System instability and oscillation caused by strong external disturbances are also reduced. Experimental results prove the effectiveness of the developed CDRC.

SMC Development Guidelines for Axial Flux PM Machines Employing Coreless Rotor Structure for Enhancing Efficiency Based on Experimental Results

In recent years, there has been growing demand for flat electrical machines in order to minimize system size while also maintaining high efficiency. In general, axial flux machines (AFMs) are more suitable for flat form than radial flux machines (RFMs). AFMs usually employ a soft magnetic composite (SMC) for the stator core, and their efficiency can be improved by employing an SMC that has low iron loss. However, this reduces the average torque because there is generally a tradeoff relationship between iron loss and magnetic permeability in SMCs. This article, therefore, proposes an AFM with a coreless rotor structure in which the torque performance is not easily affected by the permeability of the SMC. This article aims to reveal the ideal SMC characteristics for high efficiency in AFMs. First, many virtual SMC materials with different iron loss and permeability are used for simulations of AFMs in order to investigate sensitivity to material properties. The simulations by virtual SMCs take into account the experimental increase in the iron loss. As a result, guidelines for developing SMCs are constructed based on the experimental results. Finally, prototype AFMs employing new SMCs developed by following the guidelines are shown, and it is found that they offer higher efficiency in all operating area than conventional AFMs. In particular, one prototype achieves an extremely high efficiency of over 96% at 6000 r/min, 0.8 Nm in experiments.

Modeling Control over the Size and Phase Composition of Submicron Particles of Titanium Dioxide Synthesized in a Flow Plasma-Chemical Reactor

A mathematical and experimental modeling of the process of synthesis under nonequilibrium conditions of a fine powder of titanium dioxide anatase crystalline modification with a combination of reaction zones and counter hardening has been carried out. The formation of ultrafine particles occurs in regions with large values of the convective derivative of temperature (~105 K/s). The mass-average particle size was 10–70 nm in calculations and 32–45 nm in experiments. The anatase content of the powder in calculations was 70–90% and in experiments ~83%. This method allows control over the phase composition and particle size of the synthesized titanium dioxide powder used as photocatalysts, in particular, when treating wastewater from organic waste and air from harmful impurities.

Identification of collision risk factors perceived by ship operators in a vessel encounter situation

This study aims to elucidate the possible risk factors considering the point of view of a ship operator by identifying the maximum collision risk-bearing angle (MCRBA) and the distance at which the collision risk begins to increase significantly (DCRBIS), which are key factors affecting navigation safety in real maritime environments. Using two ships at sea in various vessel encounter situations (relative bearing angles of 000°, 045°, 090°, and 135°), the perceived ship collision risk (PSCR) was estimated by the ship operators. Then, the mean values of all the measured parameters were used to identify the bearing angle corresponding to the highest PSCR. The MCRBA was compared to the maximum frequency collision bearing angle (MFCBA) derived by investigating 200 reported ship collision cases in Korean waters. The highest experimental PSCR values were observed at a relative bearing angle of 135°, which corresponded to the results of collision case analyses stating that the MFCBA was equal to 112.5°–135°. Notably, the PSCR magnitude increased most significantly at a distance of 1.25–1 NM in experiments involving various vessel encounter situations. Collision risk factors such as the MCRBA and DCRBIS can thus be used in the development of collision prevention protocols for ship operators.

Weighting inversion of dynamic light scattering based on particle-size information distribution character

In particle sizing with dynamic light scattering (DLS) technique, the determination of particle size distribution (PSD), via inversing the autocorrelation function (ACF) of scattering light, is usually limited by the inherently low particle size information in ACF data and, the lack of targeted inversion on the noise restriction and the particle size information utilization. For the ACF data in DLS measurement, most of particle size information is centrally contained in the decay section and the larger noise is contained in the larger delay section. However, no consideration of the particle size information distribution in the ACF data for the routine inversion method increases the difficulty of the accurate PSD inversion, especially the broad and bimodal PSDs. Until now, it is still a difficult problem to obtain an accurate recovery of the broad and bimodal PSDs, specifically the bimodal PSD with a peak position ratio less than 2:1 and containing large particles (350 nm). In this paper, a character-weighted constrained regularization (CW-CR) method is proposed, in which, the particle size information distribution in the ACF as the base and the adjustment parameter as the exponent are used to weight the ACF. By using the weighting coefficients corresponding to the particle size information distribution along the delay time in ACF, the CW-CR method can enhance the utilization of the particle size information in ACF data, and effectively weaken the effect of noise at large delay time. With this method, the closely spaced bimodal PSD (with nominal diameters of m 350 nm:500 nm in simulation, m 300 nm:502 nm in experiment) is recovered successfully at a high noise level of 0.01. It shows that the CW-CR method, combined with the multiangle DLS (MDLS) measurement, can effectively make the best use of the particle size information hiding in the noisy ACF data, and improve the resolution of bimodal PSD as well as the capability of noise suppression. So it can make the advantages of MDLS more highlighted than the routine method in the recovery of the broad and bimodal PSDs.

Analysis and optimization of parameters in optical polishing of large diameter BK7 flat components

ABSTRACTOptical polishing and nanofinishing of glass substrates has gained impetus owing to the continuously increasing applications of precise optical components, but still, the process is elusive and skill dependent as several unaccounted parameters induce uncertainties. This study is an effort toward deterministic surface quality of glass substrates in polishing, based upon analysis and optimization of some pronounced parameters. In the experiments, BK7 glass samples (100 mm dia.) were polished for 3 hours using Ceria slurry on a conventional eccentric one arm spindle polisher employing a polyurethane pad. The experiment was designed as per Taguchi’s L9 orthogonal array for a comprehensive analysis. Three control parameters – relative velocity, normal force (pressure), and abrasive size – were varied and the resultant average roughness value (Ra), measured by a surface profilometer (Talysurf PGI-120), constituted the response. Kinematic analysis, using existing literature, yielded velocity and MALVERN ZETASIZER measured average abrasive size using dynamic light scattering principle. Relative velocity was observed to be the most significant parameter and normal force the least significant. Optimum combination was identified by deriving a deterministic relation for the best surface finish in the given time. Ra values as low as 6.8 nm in the experiment runs and 4.4 nm in the validation experiment were obtained.

Nonlinear frequency conversion using high-quality modes in GaAs nanobeam cavities.

We demonstrate the design, fabrication, and characterization of nanobeam photonic crystal cavities in (111)-GaAs with multiple high-Q modes, with large frequency separations (up to 740 nm in experiment, i.e., a factor of 1.5 and up to an octave in theory). Such structures are crucial for efficient implementation of nonlinear frequency conversion. Here, we employ them to demonstrate sum-frequency generation from 1300 and 1950 nm to 780 nm. These wavelengths are particularly interesting for quantum frequency conversion between Si vacancy centers in diamond and the fiber-optic network.

All-optical on-chip sensor for high refractive index sensing in photonic crystals

In this paper we demonstrate an optical sensor designed to detect material infiltrations with relatively high indices, based on a two-dimensional photonic crystal cavity structure. The locations and sizes of the holes surrounding a L3 cavity were modified to increase the Q factor to a value of 1500 with a high refractive index infilling of . With precise design and simulation, we overcome the difficulty of low index contrast, and observe a very clear wavelength shift of 10.4 nm in simulation and 12.4 nm in experiment between water and oil samples at resonance.

Demonstration and analysis of dual‐wavelength clock recovery based on stimulated brillouin scattering

AbstractDual‐wavelength clock recovery (CR) based on Stimulated Brillouin Scattering is realized. The maximum frequency spacing of two channels is theoretically analyzed and experimentally demonstrated. The total wavelength span of the CR scheme is investigated to be about 3.37 nm in experiment. Multiwavelength CR can be implemented within the span. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 204–207, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24888

All optical wavelength conversion and optimum longitudinal mode selection using an injection-locked Fabry-Perot laser diode

Based on the cross-gain modulation effect in Fabry-Perot laser diode (FP-LD), the 2.7GHz optical pulsed signal at 1552.30nm is converted to a continuous-wave light at 1548.22nm in experiment. The variation of wavelength conversion efficiency with injection optical power and wavelength are examined in detail. Our research results indicate that there always exists a fixed longitudinal mode for a given FP-LD under certain working conditions to maximize the extinction ratio of conversion signal and conversion efficiency when the longitudinal mode is locked by the probe light. Our theoretical analysis accords with the experiment results. Moreover, there always exist an optimum signal power and a detuning range between the probe light and the longitudinal mode to improve the conversion signal further under the same longitudinal mode locked by the probe light. The optimum longitudinal mode can be determined by the FP-LD characteristics and its working conditions.

Actinic detection of sub-100 nm defects on extreme ultraviolet lithography mask blanks

We present recent experimental results from a prototype actinic (operates at the 13 nm extreme ultraviolet wavelength) defect inspection system for extreme ultraviolet lithography mask blanks. The defect sensitivity of the current actinic inspection system is shown to reach 100 nm in experiments with programmed defects. A method to cross register and cross correlate between the actinic inspection system and a commercial visible-light scattering defect inspection system is also demonstrated. Thus, random, native defects identified using the visible-light tool can reliably be found and scanned by our actinic tool. We found that native defects as small as 86 nm (as classified by the visible-light tool) were detectable by the actinic tool. These results demonstrate the capability of this tool for independent defect counting experiments.

Angiotensin II-activated Ca2+ entry-induced release of Ca2+ from intracellular stores in rat portal vein myocytes.

1. The action of angiotensin II (AII) was studied in single myocytes from rat portal vein in which the cytoplasmic Ca2+ concentration was estimated by emission from dyes Fura-2 or Indo-1 and the Ca2+ channel current was measured with the whole-cell mode of the patch-clamp technique. 2. Most of the AII-evoked increases in [Ca2+]i were reduced by about 60% after pretreatment with ryanodine and caffeine to deplete intracellular Ca2+ stores. However, in some cells the AII-induced Ca2+ responses were of small amplitude and resembled those obtained in the presence of ryanodine and caffeine. Both types of Ca2+ responses induced by AII were selectively inhibited by losartan, suggesting that the AII effects resulted from activation of the angiotensin AT1 receptors. 3. The concentration-response curve to AII had an EC50 value close to 1 nM for the increase in [Ca2+]i obtained after depletion of intracellular Ca2+ stores. This value was increased to around 18 nM in experiments where the intracellular Ca2+ stores were not depleted. 4. AII-evoked Ca2+ responses were abolished in the absence of external Ca2+ and in the presence of 1 microM oxodipine to block L-type Ca2+ channels. 5. Intracellular applications of the InsP3 receptor antagonist, heparin or an anti-PdtIns antibody did not modify AII-induced Ca2+ responses. 6. Our results show that AII releases Ca2+ from intracellular stores without involving InsP3 but through a Ca2+ release mechanism activated by Ca2+ influx through L-type Ca2+ channels.

Fluorescence-quenching-resolved spectra of melittin in lipid bilayers

The interaction of bee venom melittin with dimyristoylphosphatidylcholine (DMPC) unilamellar vesicles has been studied by means of fluorescence quenching of the single tryptophan residue of the protein, at lipid-to-peptide ratio, R i = 50 and at high ionic strength (2 M NaCl). The method of flourescence-quenching-resolved spectra (FQRS), applied in this study with potassium iodide as a quencher, enabled us to decompose the tryptophan emission spectrum of liposome-bound melittin into components, at temperatures above as well as below the main phase transition temperature ( T t) of DMPC. One of the two resolved spectra exhibits maximum at 342 and 338 nm for experiments above and below T t, respectively, and is similar to the maximum of tryptophan emission found for tetrameric melittin in solution (340 nm). This spectrum is characterized by the Stern-Volmer quenching constant, K sv, of about 4 M −1 and it represents the fraction of melittin molecules whose tryptophan residues are exposed to the solvent to a degree comparable with tetrameric species in solution. The other spectrum component, corresponding to the quencher-inaccessible fraction of tryptophan molecules ( K sv = 0 M −1) has its maximum blue-shifted up to 15 nm, indicating a decrease in polarity of the environment. For experiments above T t, the blue spectrum component revealed the excitation-wavelength dependence, originating probably from the relaxation processes between the excited tryptophan molecules and lipid polar head groups. We conclude that melittin bound to DMPC liposomes exists in two lipid-associated forms; one, with tryptophan residues exposed to the solvent and the other, penetrating the membrane interior, with tryptophan residues located in close proximity to the phospholipid polar head groups of the outer vesicle lipid layer. We also discuss our data with current models of melittin-bilayer interactions.

Stimulus generalization of auto-shaped key-pecking following interdimensional and extradimensional training

In three experiments, groups of pigeons were tested for wavelength generalization of auto-shaped key-pecking following different types of training. In Experiment I, one group received auto-shape trials with a 555-nm CS. Another group received auto-shape trials with a 555-nm CS and a white CS. A third group received auto-shape trials with a 555-nm CS and a white CS, except the white CS was nonreinforced. The third group yielded the sharpest gradient, whereas the second group yielded the flattest gradient. In Experiment II, one group received auto-shape trials with a 555-nm CS. A second group received auto-shape trials with a 555-nm CS and a compound CS consisting of a vertical white line on a 555-nm background. A third group received auto-shape trials with a 555-nm CS and a compound CS, except that the compound was nonreinforced. The third group yielded the sharpest wavelength gradient, whereas the second group yielded the flattest. In Experiment III, exposure differences to 555 nm in Experiment II resulting from differential speeds of auto-shape acquisition were controlled by the use of an ITI manipulation. Amount of exposure to 555 nm was shown not to be responsible for the results of Experiment II.